For the purpose of studying the influence of evaporation temperature on system efficiency and turbine efficiency of ocean thermal energy conversion (OTEC) Rankine cycle in different temperature differences. The 15kW OTEC experiment system has been designed and built. By maintaining hot seawater and turbine parameters, OTEC Rankine cycle has been experimentally studied. The results showed that the system efficiency and turbine efficiency increase with the increase of seawater temperature difference, and when the temperature difference is 19.7°C, matching the design conditions: turbine efficiency is 73%, output power is 15kW. The system efficiency and turbine efficiency show a tendency of rising first and then decreasing with the increase of evaporating temperature at given temperature difference.